[turbofan] Properly cover memory operands in comparisons.

[turbofan] Properly cover memory operands in comparisons.

The InstructionSelector::CanCover() heuristic was not correctly set to
match loads that are wired into the effect chain (i.e. when the input
comes from the JavaScript pipeline instead of the RawMachineAssembler).
Also the InstructionSelector on x64 was confused by the
CanBeBetterLeftOperand heuristic, which prevented proper covering for
map checks generated by the JavaScript pipeline.

R=epertoso@chromium.org

Committed: https://crrev.com/8473ccdc4529e27ea4de4e6caff2119a4e23936c
Cr-Commit-Position: refs/heads/master@{#34242}

[Benedikt Meurer, 2016-02-24 07:39:55]

Hey Enrico,

Here's a small follow-up fix for the memory operand covering. I only looked into
x64 (and still looking into other cases). Once this settles we can port it to
ia32 (don't think it's useful to play with both at the same time).
Please take a look.

Thanks,
Benedikt

[epertoso, 2016-02-24 10:20:42]

lgtm

[Benedikt Meurer, 2016-02-24 10:20:55]

The CQ bit was checked by bmeurer@chromium.org

[commit-bot: I haz the power, 2016-02-24 10:21:05]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1734503002/1
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1734503002/1

[commit-bot: I haz the power, 2016-02-24 10:22:43]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2016-02-24 10:23:53]

Description was changed from

==========
[turbofan] Properly cover memory operands in comparisons.

The InstructionSelector::CanCover() heuristic was not correctly set to
match loads that are wired into the effect chain (i.e. when the input
comes from the JavaScript pipeline instead of the RawMachineAssembler).
Also the InstructionSelector on x64 was confused by the
CanBeBetterLeftOperand heuristic, which prevented proper covering for
map checks generated by the JavaScript pipeline.

R=epertoso@chromium.org
==========

to

==========
[turbofan] Properly cover memory operands in comparisons.

The InstructionSelector::CanCover() heuristic was not correctly set to
match loads that are wired into the effect chain (i.e. when the input
comes from the JavaScript pipeline instead of the RawMachineAssembler).
Also the InstructionSelector on x64 was confused by the
CanBeBetterLeftOperand heuristic, which prevented proper covering for
map checks generated by the JavaScript pipeline.

R=epertoso@chromium.org

Committed: https://crrev.com/8473ccdc4529e27ea4de4e6caff2119a4e23936c
Cr-Commit-Position: refs/heads/master@{#34242}
==========

[commit-bot: I haz the power, 2016-02-24 10:23:54]

Patchset 1 (id:??) landed as
https://crrev.com/8473ccdc4529e27ea4de4e6caff2119a4e23936c
Cr-Commit-Position: refs/heads/master@{#34242}